One of the advantages of modern telecommunications involving mobile telephones is of course their portability and convenience. However, the use of mobile telephones in certain conditions, such as driving a vehicle, renders their use unsafe and accordingly hands free units or cradles have been developed for fitment to the fascia or dash of a vehicle or some other convenient position about the driver in order to minimise the need for the driver to hold and therefore physically interact with the mobile telephone whilst engaged in communication on the telephone. This is generally accomplished by providing a receptacle in the form of a cup or cradle into which a mobile telephone is inserted so that the driver of the vehicle may use the telephone essentially "hands free".
As a result of providing appropriate electrical contacts between the telephone and the cradle, several functions normally handled within the mobile telephone itself are able to be transferred to external components in order to facilitate the hands free operation of the telephone by the driver. For example, a microphone is conveniently mounted in a position adjacent to the driver's head in order that he can speak into the microphone without having to have the mouthpiece of the telephone near his mouth while he speaks. Similarly, a connection is provided to an external speaker conveniently mounted for example under the dashboard which provides amplification of the other party's voice so that once again the earpiece of the mobile telephone is not required to be adjacent to the driver's ear. These connections are provided by appropriate electrical contacts between contacts terminals provided in the exterior of telephone, often at the base thereof, and corresponding contact terminals in the receptacle, thereby allowing the respective functions to be transferred from the internal components to such external components as the microphone and speaker described above.
With advantage several other functions may also be transferred from the mobile telephone itself to the wider environment of the vehicle by means of similar connections in order to improve both the performance and general useability of the mobile telephone in the vehicular situation. These include attaching the telephone to the vehicular power supply in order to avoid draining the telephone's own battery and/or alternatively providing power to recharge the battery within the telephone as required. Similarly, the antenna function provided within the mobile telephone can be superseded by connection to an appropriate antenna mounted conveniently on the exterior of the vehicle to improve reception.
In designing hands free units of this nature for receiving mobile phones, two particular problems frequently arise. The first relates to problems associated with positioning the hands free unit itself so that the telephone and hands free unit may be readily located and inserted therein. It is paramount that intimate contact between the various sockets, plugs, pins or the like is achieved so that the telephone may work properly, whilst at the same time it is necessary to avoid possible damage to the contacts. It will be readily appreciated that the technology of mobile telephones provides the advantage of portability and accordingly circuitry and contacts are generally minimised and miniaturised as much as possible to avoid unnecessary volume and weight and accordingly contact terminals are not necessarily all that robust. Thus in bringing the telephone into contact with the hands free unit, it is important that damage between the contacts resulting for example in bent pins or wires is avoided, as contact under those conditions of course will not be achieved. This problem is exacerbated by virtue of the limited number of readily available sites around the vehicle for locating the hands free unit and the corresponding accessibility of those sites for easily locating and inserting the telephone into the unit.
Furthermore, the positioning of the hands free cradle, particularly where such facility is added to a vehicle after construction, requires that the receptacle itself be designed so that it is as compact and streamlined as possible. It is also important that it be multi-functional in so far as it be able to cope with location in a variety of positions over a wide range of vehicle designs. Universal mounting brackets capable of being mounted to various fascia and/or console positions have been developed to overcome some of the design difficulties in fixing such units in such a wide variety of vehicles. Nevertheless, the ultimate location of the hands free unit is often a compromise between accessibility to the driver, avoiding interference with other controls or indeed other vehicle passengers and of course a question of aesthetics. In reaching such a compromise, it is therefore important that the design of the hands free unit itself assist in allowing relatively easy insertion of the telephone therein without unduly limiting or impairing the flexibility for locating the hands free unit.
One conventional means for ensuring that the telephone is properly aligned with the contacts of the unit has been achieved by providing what is effectively an open faced tube into which the telephone is slid. The open face arrangement is provided to maximise access to the front panel of the telephone itself where the major proportion of its controls including the keypad are generally located. However, this design severely limits the number of suitable locations to which the hands free unit may be mounted as sufficient clearance must be provided so that the telephone can be inserted into the tube. Therefore it has been found advantageous to provide a cradle of relatively open design, so that the telephone, rather than being slid along the longitudinal axis of the unit, is instead laid in the cradle from a position adjacent to the front thereof. In other words the telephone can be inserted from above or in front of the unit depending on whether it is upright or laying down, the base of the telephone generally being inserted into a corresponding but relatively short cup portion, the telephone then being rotated into position against the back of the cradle. The obvious disadvantage with this arrangement is that the contact terminals particularly where they are of the pin/socket arrangement, are readily deformed by the twisting motion as the telephone seats against the bottom and back of the cradle. The contact terminals may thus be damaged with consequent loss of use and requirement to repair.
Secondly, once the telephone is in a position where contact is made between the internal circuits and the external circuits referred to above, it is often necessary that the telephone be restrained in that position to avoid loss of contact during operation. This is particularly important in the environment of a moving vehicle where forces of inertia and other shocks and vibrations to the vehicle might result in dislocation of the telephone from its cradle thereby causing not only loss of contact disrupting communication, but danger to the occupants of the vehicle or indeed damage to the telephone or vehicle itself should the telephone become dislodged. In addition, any release mechanism for disengaging the telephone once it is required to be removed, should also be conveniently located on the hands free unit bearing in mind the constraints occasioned by the difficulties in location of the unit itself referred to above.
Consequently, much consideration has been given to designing hands free cradles capable of providing the necessary contact between internal circuitry and external components coupled with appropriate means for retaining the mobile telephone whilst maintaining that contact.